The Accuracy of Repeated Sleep Studies in OSA: A Longitudinal Observational Study With 14 Nights of Oxygen Saturation Monitoring.

BACKGROUND: Strong evidence exists for clinically relevant night-to-night variability of respiratory events in patients with suspected OSA. RESEARCH QUESTION: How many sleep study nights are required to diagnose OSA accurately? STUDY DESIGN AND METHODS: Patients with suspected OSA underwent up to 14 nights of pulse oximetry (PO) at home and one night of in-hospital respiratory polygraphy (RP). The accuracy of each of the 13 sleep study nights was analyzed using the mean oxygen desaturation index 3% (ODI3%) of all 14 nights as a reference. Multiple regression analyses assessed possible predictors for night-to-night variability. RESULTS: One hundred three patients underwent in-hospital RP. Using only the results of the RP, 19.7% were misdiagnosed using an ODI3% cutoff of 15/h. One hundred eight patients underwent properly performed PO studies at home with a coefficient of variation (CV) of 31.5% (SD, 14.7%) across all nights. The first PO night demonstrated a sensitivity of 71.4% (95% CI, 55.4%-84.3%) and a specificity of 89.4% (95% CI, 79.4%-95.6%) to diagnose moderate OSA. Using only the first PO night, the negative predictive value was 83.1%. Adding a second recording night increased sensitivity up to 88.1% (95% CI, 74.4%-96.0%) with a slightly lower specificity of 85.9% (95% CI, 74.9%-93.4%). The ODI3% of the in-hospital RP showed an independent negative association to the log-transformed CV (exponentiated coefficient, 0.989; 95% CI, 0.984-0.995). INTERPRETATION: One single night of in-hospital RP may miss relevant OSA. Multiple study nights, for example, using ambulatory oxygen saturation monitoring, increase accuracy for diagnosing moderate OSA. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03819361; URL: www.clinicaltrials.gov.

Nocturnal heart rate variability in obstructive sleep apnoea: a cross-sectional analysis of the Sleep Heart Health Study.

BACKGROUND: Obstructive sleep apnoea (OSA) results in sympathetic overdrive. Increased nocturnal heart rate variability (HRV) is a surrogate marker of autonomic disturbance. The aim was to study the association of the apnoea-hypopnea index (AHI), nocturnal hypoxaemia, and sleep fragmentation with nocturnal HRV to address the pathophysiological mechanisms underlying autonomic disturbance in OSA. METHODS: Participants of the Sleep Hearth Health Study with available data on nocturnal HRV and an AHI ≥10/h have been included in this cross-sectional analysis. The main outcome of interest was the association of sleep fragmentation, nocturnal hypoxaemia, and the AHI with nocturnal HRV. Multivariate regression modelling with the mean of the standard deviations of normal-sinus-to-normal-sinus-interbeat intervals in all 5-minute segments (SDNNIDX) and with low to high frequency power-ratio (LF/HF) as dependent variables controlling for prespecified confounders (age, sex, cups of coffee, beta blocker, nocturnal heart rate) was used to assess the contribution of the arousal index, total sleep time with an oxygen saturation <90% (TST90) and the AHI not due to arousals to HRV. The significance level was set at P<0.01. RESULTS: In 258 patients with OSA (mean ± SD age 62±10 years, BMI 29±4 kg/m2, median (IQR) AHI 18.6/h (14.0-25.6), the arousal index (coef =0.42, P=0.002) was independently positively associated with SDNNIDX also after having controlled for potential confounders, whereas the AHI (coef =0.22, P=0.030) and TST90 (coef =0.36, P=0.054) were not. The arousal index-but not TST and AHI-was also independently associated with LF/HF. CONCLUSIONS: In OSA, pronounced sleep fragmentation is associated with higher nocturnal HRV and a sympatho-vagal imbalance with sympathetic dominance. OSA severity and nocturnal hypoxaemia did not independently predict nocturnal HRV.

Patterns of nightly CPAP usage in OSA patients with suboptimal treatment adherence.

BACKGROUND AND OBJECTIVES: Low adherence impairs the effectiveness of continuous positive airway pressure (CPAP) therapy in patients with obstructive sleep apnoea (OSA), but knowledge on CPAP usage micro-patterns is mostly lacking. Thus, the aim of this study was to analyse usage micro-patterns among patients with suboptimal CPAP adherence. METHODS: We analysed CPAP usage datasets comprising the initial 31 nights of therapy. By employing a threshold of 4 h usage in at least 70% of nights, we subdivided the patients into suboptimal and optimal users. We investigated single CPAP start- and stop-points, and introduced the parameter "interruption-rate", by dividing the amount of therapy interruptions per night by the usage duration per night. This parameter represents the amount of interruptions per 1 h of CPAP usage. Group comparison analysis was performed via t-test, Wilcoxon rank sum-test, and via Chi2-test. RESULTS: We included datasets of 48 suboptimal and 48 optimal users (55.9 ± 11.3 years, 83.3% men) in the analysis. Interruption-rate was significantly higher among suboptimal users, when compared with optimal users (median (quartiles) 0.24 (0.14/0.45) versus 0.15 (0.05/0.28), p < 0.001∗). Suboptimal users were more likely to report that CPAP reduced their sleep quality, waked them up at night, and that CPAP side effects or problems with the device impaired their adherence. CONCLUSIONS: CPAP usage micro-patterns are more fragmented among OSA patients with lower overall adherence. These patterns might result from impaired sleep quality, due to CPAP side effects, and device-associated problems.

Compliance of Pharmacotherapy with GOLD Guidelines: A Longitudinal Study in Patients with COPD.

Objective: To evaluate the clinical implementation of pharmacotherapy recommendations for chronic obstructive pulmonary disease (COPD) based on the Global Initiative for chronic obstructive lung disease (GOLD) guidelines, in a longitudinal setting. Methods: This is a sub-analysis of a prospective, non-interventional cohort study including patients with confirmed mild-to-very-severe COPD from seven pulmonary outpatient clinics in Switzerland. Follow-up visits took place annually for up to 7 years, from October 2010 until December 2016. For each visit, we evaluated the compliance of the prescribed pharmacotherapy with the concurrently valid GOLD guideline. We investigated whether step-ups or step-downs in GOLD stage or risk-group were accompanied by concordant changes in prescribed medication. Groups were compared via ANOVA. Results: Data of 305 patients (62±7 years, 66% men) were analysed. In 59.1% of visits, the prescribed medication conformed to the respective valid GOLD-guideline. Patients with very severe COPD were most likely to receive pharmacotherapy in compliance with guidelines. Step-ups and step-downs in risk group, requiring escalation, or de-escalation of pharmacotherapy, were noticed in 24 and 43 follow-up visits, respectively. Step-ups were adequately implemented in 4 (16.7%) and step-downs in six cases (14.0%). Conclusion: The compliance of COPD-pharmacotherapy with GOLD-guidelines is suboptimal, especially in lower risk groups. The high rates of missed out treatment-adjustments suggest that the familiarity of physicians with guidelines leaves room for improvement.

Low repeatability of Epworth Sleepiness Scale after short intervals in a sleep clinic population.

STUDY OBJECTIVES: The purpose of this study was to evaluate the short-term repeatability of the Epworth Sleepiness Scale (ESS) in patients with suspected obstructive sleep apnea and to determine whether transitory sleepiness of the patient influenced ESS results. METHODS: Adult participants with suspected obstructive sleep apnea taking part in a study on the diagnostic accuracy of repeated sleep studies were eligible. For assessment of repeatability, the agreement between 2 sequential ESS scores obtained within 1 day (same-day group) or on different days within 1 week (same-week group) was evaluated. By analyzing the within-day repeatability, a possible influence of situational sleepiness on ESS results was assessed. By comparing correlations of sequential scores between both groups, a potential influence of test day-specific sleepiness on ESS results was evaluated. Data were analyzed using Bland-Altman plots, intraclass correlation coefficients, standard error of measurement analysis, and relative amounts of ESS discrepancies beyond 2, 3, 5, and 7 points. RESULTS: Forty participants (mean age, 47.7 ± 15.4 years; 67.5% men) were included in this study, with 20 in each group. Bland-Altman analysis demonstrated considerable variability of repeated scores (mean ± 1.96 × SD = 1.93 [-3.81 to 7.66]). Discrepancies of at least 3 points between sequential ESS scores were found in 48% of all participants. Comparison of ESS repeatability between both groups showed no evidence for a difference. CONCLUSIONS: A clinically relevant variability in ESS scores was found, even when repeated on the same day, possibly because of situational sleepiness influencing ESS results. Changes in ESS in response to interventions should be interpreted with caution because of its low test-retest reliability.